Secretin-enhanced MR Imaging of the Pancreas

Abstract

1Secretin is a hormone that stimulates the exocrine pancreatic secretion of bicarbonate-rich fluid from the acinar cells of the pancreas that accumulates within the pancreatic ductal lumen. The exogenous administration of secretin improves the visualization of pancreatic ducts at magnetic resonance (MR) cholangiopancreatography (MRCP), because of an enlargement of the pancreatic duct system and an increase of the fluid content within the lumen of the pancreatic ducts, responsible of an increase of MR signal. In this review, the technique of secretin-enhanced MRCP, which has the aim to depict the whole pancreatic duct system, the biliary tree, the major and minor papillae, and the duodenum, will be described. Because of the anatomic contiguity between the pancreas and the gastrointestinal tract, the presence of fluid within the stomach may overlap with the pancreatic duct system and therefore the pancreatic duct may be difficult to visualize, representing a potential source of diagnostic pitfalls. The technique to reduce the signal intensity of the static fluid present within the stomach and in the duodenal lumen is also described. The technique of secretin administration will be illustrated, with emphasis on the synchronization of secretin administration and MR image acquisition. Furthermore, the frequency and number of MRCP images necessary to achieve a temporal resolution adequate to visualize the physiologic changes in the pancreatic gland, induced by the administration of secretin, is described. The assessment of pancreatic, morphologic, and functional response to the administration of secretin, as depicted on MRCP images, will be illustrated. Finally, the indications for secretin-enhanced MRCP will be discussed to define which patients will benefit from secretin-enhanced MR imaging for their treatment planning. © RSNA, 2016 This copy is for personal use only. To order printed copies, contact reprints@rsna.org I n recent years, magnetic resonance (MR) imaging has increased its role in the detection and characterization of pancreatic diseases. This is most likely due to the capability of MR imaging to simultaneously assess the pancreatic parenchyma and the pancreatic and bile duct systems. This can be achieved by obtaining cross-sectional MR images by using breath-hold T1-weighted gradient-echo sequences performed as two-or three-dimensional gradient-echo, fat-suppression techniques; T2-weighted half-Fourier pulse sequences; diffusion-weighted imaging; and dynamic contrast material-enhanced imaging following the administration of gadolinium chelates that are able to depict and characterize focal pancreatic masses and evaluate diffuse pancreatic diseases. Furthermore, MR cholangiopancreatography (MRCP) is STATE OF THE ART: Essentialsn Secretin-enhanced magnetic resonance cholangiopancreatography (MRCP) is indicated in patients with chronic asymptomatic hyperenzymemia, recurrent acute pancreatitis, sphincter of Oddi dysfunction, anatomic variants, chronic pancreatitis, and main pancreatic duct stenosis.n Se...

Respiratory motion artifacts during arterial phase imaging with gadoxetic acid: Can the injection protocol minimize this drawback?

“…According to the clinical indication, we perform secretin‐enhanced magnetic resonance cholangiopancreatography (S‐MRCP) in combination with gadoxetic acid in patients referred for functional work‐up of pancreaticobiliary diseases such as sphincter Oddi dysfunction and early detection of chronic recurrent pancreatitis, etc. Because secretin must be injected very slowly to prevent adverse reactions, we always inject it by hand . Therefore, for convenience and for safety reasons we simultaneously inject gadoxetic acid (0.025 mmol/kg body weight) manually (M3).…”

Secretin-stimulated MR cholangiopancreatography: spectrum of findings in pancreatic diseases

“…Because the major part of the pancreatic secretion must flow through the minor pancreatic duct, this could predispose to obstructive pancreatopathy causing pancreatitis and pancreatic-type pain or even the development of severe chronic pancreatitis [14, 15]. …”

“…IPD is less associated with pancreatitis than complete PD, since high pressure in the dorsal pancreatic duct system can decrease via a connection to the ventral duct [12, 15, 16]. …”

“…APBJ is a rare congenital anomaly in which the pancreatic and biliary ducts are joined outside the duodenal wall [15], which may be diagnosed by distention of the gallbladder during SS-MRCP.…”

“…According to some authors, SS-MRCP is effective in diagnosing the presence of Santorinicele in patients affected by unexplained recurrent episodes of acute pancreatitis, who might benefit from endoscopic sphinterotomy of the minor papilla [15, 18]. …”